This invention relates to a vehicular a.c. generator and a manufacturing method therefor and more particularly to a vehicular a.c. generator which is mounted on a vehicle such as an automobile for a.c. generation by the power from an engine and a manufacturing method therefor.
The vehicular a.c. generator of this kind has been known as disclosed in Japanese Patent Laid-Open No. 62-178137. However, the conventional vehicular a.c. generator is complex in structure for cooling a rear bracket with a cooling liquid and requires a number of seals that need sophisticated sealing techniques and troublesome operations. In order to dissolve this problem, a vehicular a.c. generator of the structure shown in FIG. 1 is proposed. This generator is not a prior art.
A vehicular a.c. generator 1 shown in FIG. 1 comprises a rear bracket 2a having formed inside of it an annular surrounding groove 4 which defines a gap or clearance together with an outer periphery of a rear coil end 3a of a stator 3. The gap is filled with an electrically insulating filling material 5 of a good thermal conductivity and a cooling cover 6 is liquid-tightly attached to the outer end of the rear bracket 2a. Then, a cooling cover 6 is liquid-tightly attached to the outer end of the rear bracket 2a to define a cooling liquid passage 7 therebetween through which a cooling liquid is introduced from the exterior and passed through the flow passage 7 and discharged into the exterior, thereby to cool the rear coil end 3a of the stator 3, excitation iron core 8 mounted to the inner wall portion of the rear bracket 2a and a rectifier 9, a voltage regulator 10 and the like attached to the outer surface of the cooling cover 6.
In FIG. 1, reference numeral 2b is a front bracket, 3b is a front coil end, 3c is a core of the stator 3, 11 is a rotary shaft, 12 is a rotor secured on the rotary shaft 11, 13 is a field coil, 14 is a front centrifugal cooling fan attached to the side surface of the front side of the rotor 12, 15 is pulley secured on the front end of the rotary shaft 11, 16 is a bolt for securing the excitation iron core 8 to the inner wall portion of the rear bracket 2a, and 17 is a coolant outlet pipe in communication with the flow path 7. Also, the previously-mentioned rectifier 9, which converts an output current due to an a.c. voltage induced in the coil of the stator 3 into a direct current, is mounted to the cooling cover 6 through a heat sink 9a. Further, voltage regulator 10 which detects a generator voltage, controls the excitation current and regulate the terminal voltage to a predetermined value is mounted to the cooling cover 6 through a heat sink 10a.
In the above-described vehicular a.c. generator 1, the filling of the filler material 5 into the gap between the annular surrounding groove 4 formed in the rear bracket 2a and the outer periphery of the rear coil end 3a of the stator 3 has been conducted as follows.
That is, an appropriate amount of the filling material is applied to the outer periphery of the rear coil end 3a before assembly, and then this is inserted into the annular surrounding groove 4 of the rear bracket 2a, thereby filling the gap around the rear coil end with the filling material.
However, with the method for filling the filling material as discussed above, it has been difficult to evenly apply the filling material to the rear coil end, often forming cavities 18 due to insufficient or improper filling as shown in FIG. 1, resulting in a significant degrading of the cooling efficiency. Also, during insertion of the rear coil end into the annular surrounding groove of the rear bracket with the filling material applied on the rear coil end, the filling material applied on the rear coil end adheres to spigot joints in which dimensional precision is required, making proper fitting of the joints difficult.